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Thomas Cheung Chun Guang Li Charlie Xue The Chinese Medicine Research Group

Determination of Heavy Metals in Traditional Chinese Herbs & Chinese Proprietary Medicines in Victoria, Australia – How Safe Are They?. Thomas Cheung Chun Guang Li Charlie Xue The Chinese Medicine Research Group Division of Chinese Medicine RMIT University, Australia. Objectives.

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Thomas Cheung Chun Guang Li Charlie Xue The Chinese Medicine Research Group

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  1. Determination ofHeavy Metals in Traditional Chinese Herbs & Chinese Proprietary Medicines in Victoria, Australia – How Safe Are They? Thomas Cheung Chun Guang Li Charlie Xue The Chinese Medicine Research Group Division of Chinese Medicine RMIT University, Australia

  2. Objectives • (1) To determine the contents of trace metals, Lead, Arsenic, Cadmium, and Mercury in commonly used crude Chinese herbal medicines (CHM), and Chinese proprietary medicines (CPM) in Victoria, Australia • (2) To assess the potential risk posed by these local herbal products to consumers RMIT University

  3. Background • Public concerns about safety of Chinese medicines as a result of numerous reports of metal poisoning • Studies focus on either: (a) metal contents in different species of same herbs; or (b) metal contents on many herbs/products purchased from different cities of a country, or from different countries in the world (with one or two notable exceptions) RMIT University

  4. Problems of Such Approach • Approach is unsystematic and random • Results are not representative of the market supply • Metals are measured as the absolute (total) contents in crude herbs / proprietary products after hot acid or microwave digestion and toxicities interpreted from these results • Crude Chinese herbal medicines (CHM) are consumed in form of aqueous decoction (aqueous metal contents different to total??) RMIT University

  5. (A) Methodology– Collection of Samples • To assess safety of TCM, a large scale, systematic screening of heavy metal in both acid-digested and water-extracted solutions of CHM & CPM purchased locally: (A) 100 over-the-counter CHMs & 50CPMs commonly used in Chinese clinical practice were purchased from 2 major herbal wholesalers in Melbourne, Australia (B) Acid-digested metal conc (total) were analysed for CHMs and CPMs (C) Water-soluble metal conc(aqueous decoction) were also analysed for CHMs RMIT University

  6. (B) Methodology–– Analytical Techniques • Graphite furnace atomic absorption spectrometry analysis – lead (Pb), arsenic (As), & cadmium (Cd) • Cold vapour generation atomic absorption spectrometry analysis – mercury (Hg) RMIT University

  7. Method of Data Analysis of Results • Water-soluble metal conc (a) in CHMs compared to acid-digested conc (b). The (a) were used to calculate weekly metal intake based on average daily dosage of CHMs recommended in clinical practice, ~10g • Acid-digested metal conc in CPMs were used to calculate weekly metal intake based on daily dosage recommended by manufacturers RMIT University

  8. Methodof Risk Assessment of Results • Calculated weekly metal intakes (WI) of each metal from aqueous CHMs & acid CPMs were compared to regulatory standards of Provisional Tolerable Weekly Intakes (TDI) set by WHO, & ANZFA, as % of TDI to evaluate safety/risk • The above % of TDI from CHMs & CPMs were added to the daily exposure of the same metal derived from normal daily total dietary exposure estimated by the 20th Australian Total Dietary Survey (ATDS) to obtain a realistic combined daily total metal intake for final risk assessment RMIT University

  9. Results RMIT University

  10. Fig 1. Distribution of acid-digested metal contents in 100 CHMs RMIT University

  11. Fig 2. Distribution of Acid-digested and Corresponding Water-soluble Metal Contents in 100 CHMs RMIT University

  12. Fig 3. Distribution of acid-digested metal contents in 50 CPMs RMIT University

  13. Table 1. Exposure as % of TDI from Australian Total Dietary Survey (ATDS)a, from Aqueous CHMsb, and from combinedc ATDS and Aqueous CHMs RMIT University

  14. Table2. Range of total (Diet + CPM)cdaily exposures to metals as a percentage of the tolerable limits after the lowest and highest levels of metals detected in Chinese Proprietary Product (CPM) in the present projectb are added to the percentage range of mean estimated daily dietary exposuresa to the same metals reported in The 20th Australian Total Diet Survey (ATDS)a RMIT University

  15. Conclusion • The perception that TCM are highly contaminated with metals is questionable. • Interpretation of safety of TCM in terms of metal contents should consider the traditional process of boiling with water. • Consumption of Chinese medicines in the form of aqueous decoction of crude herbs or patent medicines do not pose health risks to consumers according to WHO & ANZFA regulatory standards. This is true for at least 50% of the herbs marketed to consumers as represented in the collection of this project. RMIT University

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